Automatic firearm



Feb. 18, 1936. END r AL &031305 AUTOMATIC FIREARM Filed Aug. 28 1933 ratentec reb. 18, 1936 P ATENT OFFICE i h 2,'031305 AUTO'MATIG Gotthard End and Jakob Gaetzi,

Schaifhausen,

Switzerland, assignors to Schweizerische Industre-Ges'ellsclaft, Nei'hiausen, Switzerland, a Corporation 'o'f "Switzerland Application August- 28, 1933, Serial No. 6875218 In-Great Britain September 3, 1932 7 *Claims. r 'The present invention relates :to :rearms .and

;particularly to automatic, gas operated firearms `-whereingases of one discharge storezpowerin aneIement :such as a 'striker post or the like 'for actuating the 'breech mechanism :and driv- :ing the feeding and firing mechanismin the :sucsceeding discharge.

The invention more particularly relates to au.- :tomatic gas operated firearms having a' 'statio'ne ary barrel and a locked breech bolt.

The main object of the invention is the pro duction of a firearm of the type aforesaid of --very simple Construction, of extreme accuracy and of absolute reliability.

Not only with mitrailleuse, :but even with-auto'- matic firearms, it may happen that the barrel becomes so hot that a cartridge inserted in the -cartridge carrier discharges without the firing apparatus having ope'ated. This spontaneous -firng can, therefore, take place with the weapon at safety, a circunistance which is extremely dangerous both to the man handling .the weapon and to those around him. u i

In order to avoid this danger with weapons of the mitrailleuse type and also with 'other machine guns which do not have special provision, such as a water jacket, .for cooling the barrel there has been ,provided the so-called open breech closure" mechanism. This breech closure mechanism is normally held in itsrear position `and only by the actuation of the trigger does it close and simultaneously fire the cartridge, which it introduces, on its closing movement, from the `magazine` to the Cartridge chamber. In other words, there is never a cartridge in the chamber except at the moment of ignition.

With the automatic firearm, the danger that the barrel will become so hot that .it is able spontaneously to ignite a cartridge is in general not so great as with a machine gun or amitrail- `leuse but the danger is always present; It is even created by the fact that the automatic` 'fi're'- arm tempts a man to fire a large number of 'shots in rapid succession it being possible to fire '100 "shots per minute in separate discharges, this'pos- *sibility giving a'very useful firing power'advantage of which is fully taken by 'tacticia'ns To the "open breech closure" m'echanism, however, there is attached the disadvantage' that 'the firing precision imparted to an automatic "weapon 'is poor, which weapon, in dimensions and weight,

is comparable with the ordinary 'repeating rifle. From the moment 'of the discharge, when the me'chanism is in opened position up to-the moment *when -the Cartridge r l's fired, there -1s-a 'comparatively long interval of time. The 'weapon can easily in the meantime have left the intended :lineof fire. 'In `addition, the rebound of the comi- ;p'aratively heavy breech bolt, which is thrown forward by a fairly strong spring, can produce 'such a shakingof the "weapon that the intended line of fire is 'further departed from.

Fromran'automatic weapon which, on account :of its highifiring power, is allocated to apartic'- ularly expert marksman, great precision is ex- .pected. This lprecision should'be equivalent to that of an ordinary repeating weapon.

Inorder to satisfy. the latter condition, we have developed-a form of Construction which divides the closing movement of the breech closuremech- 4, anism into two phases, of which only the latter phase, `a very brief one, is used for the actual firing of 'the Cartridge.

This and other objects as hereinafter pointed o'ut more `'specifically are 'attained by a firearm as described hereinafter and shown in a dia- `grammatical manner in the annexed drawing.

Inthe drawing:

Figs. l and 2 illustrate the `principle of the invention, 'the rear of the barrel being shown 72 with the breech mechanism in side elevation, partsbeingshown in section;

Figs. 3 and l show the back part of 'the weaponin longitudinal vertical section with closed and open breech;

Figs. 5 and 6`areside views of the breech mech'- an'i's'min closed and open 'positions respectively;

Figs. 7' and `8 show the striker post and a breech looking member separately in plan; V i

Figs 9 and -10 are cross-sections on the lines .35 -IX IX `and X-X of Figs. 7 and 8 respectively.

As` shown in Fig. 1, 'a gas chamber casing '2 is rigidly attached 'to the :barrel l, communicating therewith by a hole 23, andhaving a gas piston-3 fitted therein. The breech mechanism 'of the 40 *weapon consists of a breech block 'I and a post 5. Thebreech block 4 is shown in the locked'position and is held in this position by the post 5. In 'the 'looking 'of the breech block &the latter abuts -jagain'sta wallof'the fixed breech casing E, which is 'rig-idl'y attached to 'the barrel l. A closing spring-Tretaihs the breechblock and. the post 5 in this forward position (Fig. 3), While a spring 8 puhe'sorward the gas pisten r'od 9 and the gas pist'ona. The-firing takes place in the position fio `'o'f the mechanisin shownin Figs. l and 3.

Figs. 2 and 4; show themechanism when the bree'eh block `4 'is in its open position. In this position the 'breech block 4 with the post 5 are held *bythe trigger 35 (Figu a) against the action of the compressed spring 1. The gas piston 3 is held in the front position by the piston spring 8.

In the locked position the breech block 4 (Figs. 3 and 5) lies at an inclination. The pressure transmitted from the rear of the Cartridge on to the breech block is transmitted by the rear upper face, the so-called locking face ID, on to the breech casing 6 rigidly connected to the barrel l. The back part of the breech block 4 projects in the said inclined locked position through an opening !4 (Figs. 3 and 4) of the breech casing 6 and is prevented from shifting upward by two side lugs !3 (Fig. 3) on the edge of the opening l4. Underneath, the breech block 4 is supported on the supporting surface !5 of the post 5 and is thus Secured in the locked position.

With the breech mechanism unlocked the parts take up the position shown in Fig. 6. The breech block 4 is horizontal. The turning of the breech block 4 out of the locked position takes place about a horizontal axis in the plane of the front end face 40. The breech block rocks on this axis in a Vertical plane which contains the axis of the barrel. The post 5 is constructed and arranged to hold down the cartridges in the magazine and is arranged not toaccompany the turning movement of the member 4. This post 5 holds the cartridges in the low position necessary for the subsequent rise of a cartridge in front of the delivery member 3! forming part of the bolt. The bolt 5 is movable on fillets ll in grooves 12 on 4 and in casing 6 respectively to such an extent that it releases the column of cartridges in the magazine when the uppermost Cartridge 42 has to rise in front of the breech mechanism as soon as the mechanism reaches its rearmost position. Two lugs l on the under side of the breech block 4 act as guides for part 29 and engage the topmost Cartridge on the forward stroke of the mechanism so as to position the Cartridge for firing.

This straight movement of the post 5 is utilized for the looking of the breech block 4. The post 5 assumes together with locked breech block 4 the front position shown in Fig. 5 and it rests with its face l'l against the lower part of the looking face of the breech block 4. The sup- -porting face !8 of the post which secures the breech block 4 in the locked inclined position, runs horizontally. The looking is effected by the post 5, when the member 4 has reached its forward position, raising, by means of the looking ramp !9, the looking ramp 20 at the back part of the breech block 4 (Fig. 5). The breech block 4 assumes the locked position when its lower surface rests on the upper surfaces !3 of the post 5. The further forward movement of the bolt 5 no longer varies the position of the breech block 4 and it consequently merely supports said breech block.

In the opening movement of the breech the post 5 first moves below the face !5 of the breech block 4, without influencing said block. Thereupon the unlocking ramps 2! of the post 5 run on to 22 of the breech block 4 and deflect the back part of the latter downwardly. The member 4 thus unlocked is rigidly coupled with the post 5 and makes the opening movement therewith.

After the shot has passed the aperture 23 of the barrel, explosive gases fiow into the gas cylinder 24 of the gas chamber housing 2 (Fig. 1) and force back the gas piston 3. This acts against the post 5 Operating as a driving weight since it imparts thereto over a short distance a definite momentum. The gas piston 3 then comes to a stop, the driving weight, i. e. the post 5, owing to its momentum, leaves the rod 9 of the piston 3 and continues its movement to the rear. The post 5 is now able, in consequence of its mass and Velocity, to impart to the breech block 4 the energy necessary for the automatic operation. After a definite distance has been travelled it unlocks the member 4, carries it into the rear position and at the same time compresses the closing spring i, by means of the lug 26. The closing spring 'l is arranged centrally and bears at the back against the rear 27 of the casing 6. The lug 26 carries the firing pin 23. The post 5 acting as a driving weight, is therefore also the striking mass for effecting the firing. This firing is only possible with the breech block locked since the firing pin 23, firmly connected to the post 5, can only pass beyond the front face of the breech block when the post is in its most forward position.

As an extension of the gas piston 3 the gas piston rod 9 reaches into the range of the breech mechanism. It runs for its whole length under the barrel l and is oarried in a hole of the casing 6, between the casing 6 and the barrel l specially constructed for this purpose. The post 5 has a bolt projection 29 which, directed forward and cutting through the cartridge guide surface 30 of the casing 6, reaches a point underneath the rear end of the barrel l (Fig. 3). In the foremost position of the post it rests with its front face 3| against the rear end 32 of the gas piston rod 9. The gas piston movement taking place on the firing ,is transmitted through the points 32, 21 directly on to the post 5. Due to this transmission of movement to the post member 5 great advantages are obtained in the Construction of the weapon. The line of force runs from the gas piston 3 in a direct straight line to the post 5 and this in the centre plane of the weapon. For the purpose of transmitting energy it is not necessary, as with other forms of Construction, to go round the side of the magazine, which is for example Very difiicult in the case of a double-row magazine. The lock projection 29 runs according to Fig. 9 between the two fillets !6 of the breech block 4. In consequence of the short stroke of the gas piston the rear face 32 of the gas piston rod 9 only runs into the position indicated in dotted lines in Fig. 4. From such point the front end 3! of the post 5 leaves the gas piston rod 9 and runs the remainder of the back stroke by itself. The gas piston 3, together with the gas piston rod 9 is again pushed forward by the piston spring 8 when the action of the gas pressure in the cylinder 24 is terminated. The bolt projection 29 has on the subsequent unl'ocking of the breech block passed behind the front face of the breech block, corresponding to the displacement of the post 5 with respect to the breech block on the unlocking. consequently when it reaches the rear position it releases the upper Cartridge for lifting in front of the fillets H of the breech block 4, whereby it is loaded on the completion of the next closing process. The Cartridge guide surface 30 is so constructed that the recess for the bolt projection 29 in no Way affects the insertion.

The lug 26 against which the closing spring 1 bears is arranged well forward, so that this spring 1, in spite of its central arrangement, is sufllciently long. The breech block 4 gives it sufficient room, within its range, by a half-round ing spring 1.

ner surface 31 of the end piece 21.

rece'ss. :With thecomparatively small weight which the breech block has owing to its Construct'on i t gainsin stren gth, since its section (Fig. is of inverted U-shape. i The looking and unlocking surfaces 28, 22 are on the two symmetri call y arranged webs` of this cross-sectionally U- face *33 (Fig. 3) of the member 4, which is obtai-ned 'by further ,boring out the back breech part s. The guide sleeve 33 therefore only carries out 'the back movement of the member 4, which issmaller 'than that of the post 5. In the i back position of the bolt the guide 33 has sufcient room between the surface 39 and the in- Owing to this guide sleeve 33 the closing spring 'l is well held in the closed position of the breech also,

V since between the outer guide block 33 and the inner guide rod 36 there is practically no unsupported Stretch. In assembling the weapon the breech block 4 and the post 5 can be introduced in mutually unl'ocked position through the back opening in the casing 6 closed by the end plate 21.

The guide sleeve 33 can then be drawn back in the post 5 up to a stop\ not shown in such manner that it is itself sufliciently held in the guide sleeve 25 of the post 5. i The inserted closing spring T, in spite of the greater untensioned length, is supported over'the whole untensioned length, after the insertion of the casing cover 21 with the guide rod 36. In this way the usual difficult insertion of the closing spring in the case of weapons with partial external and partial internal closing spring guide, is avoided. As the tubular guide 33 is carried in the post 5 so as be easily movable, the latter is easily movable on the guide 33 on the next loading movement, the said guide when still in the assembled position having previously reached the end plate 21 and being retained there.

The post 5 is retained in its rear position by a trigger rod. On the subsequent release of its detent the post 5 moves forward under the action of the closing spring 'I and fires with the firing pin 28. For this purpose the length of the supporting surface !8 may also be increased, thus giving a good striking eifect. It is however possible to retain the arrangement described with extended supporting surface |8. Fig. 9 shows this arrangement with locked breech block 4 and post on bolt 5 retained by a sear. Fig. 10 corresponds to the moment of firing, the sear having freed the bolt.

What we wish to claim and secure by U. S. Letters Patent,

1. In an automatic firearm, a barrel, a magazine at the rear end of the barrel, a breech mechanism including a breech block and a longitudinally movable post carrying said breech block to move it into and from breech closing positiongsaid breech block being also independently movable relative to said post to a limited extent; a gas cylinder on the barrel and in communication with the bore thereof to receive gas from the fore part of the barrel, a piston movable in said cylinder, a piston rod extending par- 'all'el to the barrel and connected with one end to said piston, the other end being free and being adapted toengage the forwardend of said post which post is adapted to close and open saidmagazine, means independent of said post to return .said piston to its initial position after having actuated said post, said piston and piston rod being arranged to impart such momentum to the post as to cause it to move the breech block re'arwardly into open position and to un- -coverthemagazine so that the next cartridge may be :moved into a position for feeding it into the barrel.

2. In an automatic firearm, a barrel, a magazine at the rear end of the barrel, a breech mechanism :including a breech block and a lcngitudina1lymovable post carrying said breech block to move itinto and from breech closing position, saidlbreech block being also independently movable relatively 'to said post to a limited extent; a gas cylinder on the barrel and in communication with the bore thereof to receive gas from the fore part of the barrel, a piston movable *in said cylinder, a piston rod extending parallel to the barrel and connected with one end to said piston, the other end being free and being adapted to engage the forward end of said post which is also adapted to close and open said magazine, means independent of said post to return said piston to its initial position after having actuated said post said piston and piston rod being arranged to impart such momentum to the post as tocause it to move the breech block rearwardly into open position and to uncover the magazine so that the next Cartridge may be moved into a position for feeding it into the barrel, means for looking said post in its rearward position, and a spring for imparting forward movement to said post after release of said looking means, said spring being arranged in axial alinement with the barrel.

3. In an automatic firearm as set forth in claim 1, including a breech casing provided at the upper end of its rear wall with a looking face adapted to be engaged by the rear end of the breech block when the latter is moved by said post forwardly into breech closing position, said breech block and post being provided each with rigid cooperating cam means adapted to move said breech block during the forward movement of said post into an inclined position with the rear end of said breech block raised in engagement with said looking face, whereby the breech 'block is locked in breech closing position.

4. In an automatic firearm as set forth in claim 1, including a breech casing provided at the upper end of its rear wall with a looking face adapted to be engaged by the rear end of the breech block when the latter is moved by said post forwardly into breech closing position, said breech block and post being provided with cooperating rigid cam means adapted to move said breech block during the forward movement of said breech block raised in engagement with said looking face, whereby the breech block is locked in breech closing position, said post being provided with a firing pin in permanent alinement with the axis of the barrel said firing pin reaching its firing position at the end of the forward stroke of the post immediately after the breech block has been moved and locked by said post in breech closing position.

5. In an automatic firearm as set forth in claim 1, including an extension on the forward end of said post arranged in axial alinement with said piston rod, the longitudinal axis of said extension and 'piston rod being positioned between the axis of the barrel and the magazine. i

6. In an automatic firearm as set forth in claim 1, including a Cartridge guide surface at the upper portion of the front wall of said magazine and below the rear end of the barrel, and an extenson on the forward stroke of said post, said eX- I tension during the forward stroke of said post passing through said cartridge guide surface and moving under the rear end of said. barrel in abutment with the free end of said piston rod which reverses the direction of movement of said post.

'7. In an automatic firearm, a barrel, a magazine at the rear end of the barrel, a breech mechanism including a breech block and a. longitudinally movable post carrying said breech block to move it into and from breech closing position, said breech block being also independently movable relatively to said post to a limited`extent;

a gas cylinder on the barrel and in communication with the bore thereof to receive gas from the fore part of the barrel, a piston rod extending parallel to the barrel and connected With one end to said piston, the other end being free and being adapted to engage the forward end of said post which is also adapted to close and open said magazine, means independent of said post to return said piston to its initial position after being actuated by gas pressure, said piston and piston rod being arranged to impart such mom'ntum to the post as to Cause it to move the breech block rearwardly into open position and to uncover the magazine so that the next Cartridge may be moved into a position for feeding it into the barrel, said post and said piston rod being arranged in a common plane and in proximity to the axis of the barrel,

GOTTHARD END. JAKOB GAETZI. 

